Based on your screenshot, I would suggest only adding the ‘Books’ category, since all the sub-categories are also included, and it is redundant.
The search will still include results, which does not belong to any other categories, or does not have any connection with the given taxonomy. To avoid that, make sure to also turn OFF this option.
That should do the trick.
Best, Ernest Marcinko If you like my products, don't forget to rate them on codecanyon :)